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Results for “longitudinal data”

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PubMed2002

Late urologic morbidity in 177 consecutive patients after radiotherapy for cervical carcinoma: a longitudinal study.

PURPOSE: To provide longitudinal data on urologic morbidity after radiotherapy and brachytherapy for cervical carcinoma. METHODS AND MATERIALS: Five-year longitudinal urologic morbidity data were recorded from 177 consecutive patients of median age 59 years (range: 22-86 years) with cervical carcinoma receiving radiotherapy with curative intent at the Copenhagen University Hospital, Denmark. FIGO stages (%) were as follows: Stage I (15), Stage II (30), Stage III (54), and Stage IV (1). Late morbidity was calculated as cumulative incidence based on actuarial estimates. RESULTS: The 5-year cumulative incidence based on actuarial estimates of urologic morbidity Grades 1 + 2 + 3, Grades 2 + 3, and Grade 3 were 62%, 32%, and 5%, respectively. Frequencies of urologic morbidity in the 54 recurrence-free survivors at the end of follow-up indicated some reversibility in the case of Grades 1 and 2 morbidity. CONCLUSION: With the longitudinal design used in the present study, a rate of mild and moderate morbidity higher than that found in most of the previously reported literature was observed, giving cause for concern and underlining the importance of further longitudinal studies on this subject, specifically studies that relate to the background urologic morbidity in the female population, as well as to the fact that urologic morbidity might regress.

Adult↗

PubMed1995

Early acquisition of verbs in Korean: a cross-linguistic study.

This cross-linguistic study investigates children's early lexical development in English and Korean, and compares caregivers' linguistic input in the two languages. In Study 1, the lexical development of nine Korean children was followed from 1;2 to 1;10 by monthly visits and maternal reports. These Korean data were compared to previously collected English longitudinal data. We find that: (1) Korean children as young as 1;3 use verbs productively with appropriate inflections. (2) Seven of the nine children show a verb spurt at around 1;7; for six of these children the verb spurt occurs before the noun spurt. No such early verb spurt is found in the English data. Unlike in English, both verbs and nouns in Korean are dominant categories from the single-word stage. (3) Korean children express language-specific distinctions of locative actions with verbs. Study 2, a crosslinguistic study of caregivers' input in English and Korean, shows that Korean mothers provide more action verbs but fewer object nouns than American mothers. Also, Korean mothers engage in activity-oriented discourse significantly more than American mothers. Our study suggests that verbs are accessible to children from the beginning, and that they may be acquired early in children who are encouraged to do so by their language-specific grammar and input.

Child Language↗

PubMed2001

A random-effects mixture model for classifying treatment response in longitudinal clinical trials.

A random-effects regression model that allows the random coefficients to have a multivariate normal mixture distribution is described for classifying treatment response in longitudinal clinical trials. The proposed model is capable of dealing with longitudinal data from unknown heterogeneous populations. As applied to longitudinal clinical trials, for example, the model can distinguish subgroups of treatment response. Use of the proposed model is illustrated by analyzing data from two psychiatric clinical trials. The first includes depressed patients assigned to drug treatment who are repeatedly measured in terms of their level of depression. The second trial examined schizophrenic patients longitudinally who were assigned to either a drug or placebo condition. For both, the random-effects mixture model allows an assessment of whether patients comprise distinct populations in terms of their treatment response. Based on parameter estimates of the mixture model, ample evidence for a mixture of response to treatment is observed for both datasets.

Algorithms↗

PubMed2004

Incident arthritis in relation to excess weight.

OBJECTIVES: This article reports incidence rates of arthritis, based on data for people aged 40 or older who were followed over six years. The association between excess weight and arthritis, controlled for possible confounders, is also studied. DATA SOURCES: Data are from the household components of cycle 1.1 of Statistics Canada's Canadian Community Health Survey (2000/01) and from the first four cycles of the National Population Health Survey (1994/95 to 2000/01). ANALYTICAL TECHNIQUES: The prevalence of arthritis in 2000/01 was estimated using cross-sectional data; 1994/95-to-2000/01 incidence density is based on longitudinal data. Logistic regression was used to study the association between excess weight and arthritis (respondent-reported, doctor-diagnosed), while controlling for age, household income, smoking, number of physician consultations, strenuous daily activity, and other factors. MAIN RESULTS: In 2000/01, 19% of men and 31% of women aged 40 or older reported having been diagnosed with arthritis. Incidence rates of arthritis were 31 and 48 cases per 1,000 person-years for men and women, respectively. For both sexes, the odds ratio for obesity (based on self-reported height and weight) in association with subsequent arthritis was significantly elevated, at 1.6.

Adult↗

PubMed2005

Predictors of contact difficulty and refusal in a longitudinal study.

BACKGROUND: Attrition presents a serious problem to researchers collecting longitudinal data. Participant loss threatens both the internal and external validity of research findings. This study sought to examine predictors related to contact difficulty and refusals in a longitudinal study. METHOD: Data for this paper came from the Developmental Trends Study, a longitudinal study investigating the development of disruptive behaviour disorders in a sample of 177 clinic-referred boys. Annual follow-up assessments were conducted, ages for the periods examined ranged from 11 to 19 years. The predictor domains during project years 1-4 included demographics, child functioning, parental functioning, parenting skills and participant dispersion. RESULTS: These indicated that participant's older age, low socioeconomic status, the presence of callous and un-emotional behaviours, and having a father with antisocial personality disorder predicted contact difficulty, while participant's older age, living in a rural environment and attention deficit hyperactivity disorder were predictive of refusals. Participant dispersion was not significantly related to either contact difficulty or refusal status. CONCLUSIONS: Investigating a broader range of variables may better allow researchers to identify participants who may be at risk of attrition. Early identification of 'difficult' participants enables development of retention strategies to minimize attrition.

Adolescent↗

PubMed2002

Mental health, educational, and social role outcomes of adolescents with depression.

BACKGROUND: This study used longitudinal data to examine the extent to which young people with depression in mid adolescence (ages 14-16) were at increased risk of adverse psychosocial outcomes in later adolescence and young adulthood (ages 16-21). METHODS: Data were gathered during a 21-year longitudinal study of a birth cohort of 1265 children. Measures included assessments of DSM-III-R major depression (at age 14-16); psychiatric disorders, educational achievement, and social functioning (at age 16-21); social, familial, and individual factors; and comorbid disorders. RESULTS: Thirteen percent of the cohort developed depression between ages 14 and 16. Young people with depression in adolescence were at significantly (P<.05) increased risk of later major depression, anxiety disorders, nicotine dependence, alcohol abuse or dependence, suicide attempt, educational underachievement, unemployment, and early parenthood. These associations were similar for girls and boys. The results suggested the presence of 2 major pathways linking early depression to later outcomes. First, there was a direct linkage between early depression and increased risk of later major depression or anxiety disorders. Second, the associations between early depression and other outcomes were explained by the presence of confounding social, familial, and individual factors. CONCLUSIONS: Young people having early depression were at increased risk of later adverse psychosocial outcomes. There was a direct linkage in which early depression was associated with increased risk of later major depression and anxiety disorders. Linkages between early depression and other outcomes appeared to reflect the effects of confounding factors.

Adaptation, Psychological↗

PubMed2004

Effectiveness of the male latex condom: combined results for three popular condom brands used as controls in randomized clinical trials.

BACKGROUND: Although public health programs invest heavily in the male latex condom, its efficacy in preventing pregnancy and sexually transmitted disease has been based primarily on in vitro and retrospective studies. METHODS: We combine the results from two randomized, controlled contraceptive efficacy trials that used commercial latex condoms brands (Ramses Sensitol, LifeStyles, Trojan-Enz) in the control arms. Combining data from the two studies, we obtained longitudinal data covering 3526 menstrual cycles contributed by approximately 800 couples who used latex condoms exclusively for up to six menstrual cycles. Both trials also collected 3715 detailed breakage and slippage reports from the first five study condom uses. The second trial also tested 243 postcoital vaginal samples collected after the first study condom use for the presence of prostate-specific antigen (PSA) and spermatazoa. RESULTS: The combined clinical breakage rate for the first five condom uses was 0.4% for the three latex brands and the combined clinical slippage rate was 1.1%. The combined six-cycle typical-use pregnancy rate for the latex condoms was 7.0% (95% confidence interval 5.0-9.0). The combined six-cycle consistent-use pregnancy rate was 1.0% (95% confidence interval 0.0-2.1). PSA was detected in only 1.2% of postcoital vaginal samples collected after the first use of an intact study condom. There were no differences in performance or efficacy among the three latex brands tested. CONCLUSIONS: The male latex condoms rarely broke or slipped off during intercourse and provided high contraceptive efficacy, especially when used consistently. Risk of semen leakage from intact condoms was very low.

Adolescent↗

PubMed1983

Impact of divorce on locus of control orientation in adult women: a longitudinal study.

Using longitudinal data for adult women from the National Longitudinal Surveys of Labor Market Experience, this study examined the relation between getting divorced and changes in the individual's locus of control orientation. The sample contained 1,814 white women ages 32-46 years who were in their first marriage in 1969. Marital status and locus of control (an 11-item abbreviated version of Rotter's Internal-External Locus of Control Scale) were measured in 1969, 1972, and 1977. Based on previous literature on locus of control and life events and on divorce, stress, and mental health, the author hypothesized that divorced people, in comparison with those who remained married, would show a short-term increase in externality from 1969-1972, followed by a return over the next 5 years to levels of locus of control comparable to that of the group who remained married. It was also hypothesized that locus of control scores would not predict the likelihood of becoming divorced over the 8-year period. All three hypotheses were confirmed. The findings were discussed in the context of two larger theoretical issues: the influence of important life events on locus of control and the causal direction in the well-documented association between divorce and mental health.

Adult↗

PubMed1995

The longitudinal course of marital quality and stability: a review of theory, method, and research.

Although much has been learned from cross-sectional research on marriage, an understanding of how marriages develop, succeed, and fail is best achieved with longitudinal data. In view of growing interest in longitudinal research on marriage, the authors reviewed and evaluated the literature on how the quality and stability of marriages change over time. First, prevailing theoretical perspectives are examined for their ability to explain change in marital quality and stability. Second, the methods and findings of 115 longitudinal studies--representing over 45,000 marriages--are summarized and evaluated, yielding specific suggestions for improving this research, Finally, a model is outlined that integrates the strengths of previous theories of marriage, accounts for established findings, and indicates new directions for research on how marriages change.

Adult↗

PubMed2001

Longitudinal trends in and tracking of energy and nutrient intake over 20 years in a Dutch cohort of men and women between 13 and 33 years of age: The Amsterdam growth and health longitudinal study.

The purpose of the present study was to describe the longitudinal development of nutrient intake and to determine the stability of this intake from adolescence into adulthood. Longitudinal data of the Amsterdam Growth and Health Longitudinal Study were analysed; the dietary intake of 200 subjects (males and females) was repeatedly measured (eight times) over a period of 20 years, covering the age period of 13-33 years. Dietary intake was determined with the detailed crosscheck dietary history interview. With use of multivariate ANOVA for repeated measurements, trends in macro- and micronutrients over time and differences between genders were analysed. Furthermore, stability coefficients, corrected for time-dependent (biological age) and time-independent covariates (gender) were calculated, taking into account all the measurements. The results showed significant time and gender effects for energy intake (kJ) and the following macronutrients: protein (g and % total energy supply), fat (g) and carbohydrate (g). Interaction effects between time and gender diminished when the macronutrients were calculated as a percentage of total energy intake. The micronutrients Ca, Fe and vitamins changed significantly over time and showed an interaction effect with gender, with the exception of cholesterol intake (mg/MJ), which did not show an interaction effect of time and gender. The tracking of the nutrient intake showed relatively low but significant stability coefficients for all macro- and micronutrients (0.28-0.52). In conclusion, dietary intake does change considerably over time, with the exception of polyunsaturated fat intake (% total energy supply) for both males and females and fat intake in females. Furthermore, stability coefficients for nutrients appeared to be low to moderate. Although these coefficients may be somewhat attenuated as a result of the relatively large measurement error of the dietary intake measurement, they suggest moderate stability of diet over time. These findings may imply that dietary intake is changeable and suggest that disease prevention measures can be implemented in adulthood.

Adolescent↗

PubMed2002

Data quality in evaluation of an alcohol-related harm prevention program.

The authors report the reliability and convergent validity in a sample of college students for 27 composite scales and two items covering alcohol use, cigarette smoking, marijuana use, and other drug use; beliefs relating to alcohol use; perceived norms for alcohol-related behavior; harm prevention skills; intentions to take prevention action; harm prevention action taken; risk taken; experienced harm; and other health-related behaviors and person characteristics. Data quality assessment strategies and missing data procedures were illustrated for large, multivariate, longitudinal data sets. Results indicate 23 of the 27 composite scales had at least acceptable reliability, and the remaining 4 composite scales had at least marginally acceptable reliability. At least moderate construct validity was demonstrated for 25 scales.

Adult↗

PubMed2003

Hazards of hospitalization for ambulatory care sensitive conditions among older women: evidence of greater risks for African Americans and Hispanics.

Hospitalization for Ambulatory Care Sensitive conditions (ACSH) has been widely accepted as an indicator of the accessibility and overall performance of primary health care. Previous studies have found conflicting evidence about ACSH disparities associated with race or ethnicity for older persons. This study estimates discrete-time ACSH hazards for women aged 69 or older, using longitudinal data with multivariate controls. Data are from the 1984 to 1990 Longitudinal Study of Aging, linked with Medicare claims. The multivariate results are adjusted for age, education, insurance and marital status, and other factors associated with health status and primary care access, and also for important indicators of need that include self-rated health, comorbidities, physical impairments, and previous hospitalizations. Many of these factors are permitted to vary across time for each individual, thus limiting measurement error. Results suggest that older African American and Hispanic women have markedly higher ACSH risks than older non-Hispanic white women.

Black or African American↗

PubMed1988

The long-term outcome of Maudsley depressives.

Eighty-nine consecutive admissions with primary depressive illness were prospectively ascertained and diagnosed in 1965-66 by R. E. Kendell, who also allocated each a position on a neurotic-psychotic continuum on the basis of previous discriminant function analysis. In 1983-84, 94% of the survivors were personally interviewed by a psychiatrist blind to index admission data. Operational outcome criteria were employed and longitudinal data were established for 98% of the series. Mortality risk was doubled overall, and increased sevenfold for women under 40 years at index admission. Less than one-fifth of the survivors had remained well, and over one-third of the series suffered unnatural death or severe chronic distress and handicap. Patients whose index episode marked their first psychiatric contact had a 50% chance of readmission within their lifetime, but those with previous admissions had a 50% chance of readmission within three years. Readmissions occurred even after 12 years of being symptom-free, and conversely patients recovered after as long as 15 years of illness. There was a high incidence of other disorders (schizoaffective disorder, alcoholism, schizophrenia), and only four patients showed pure recurrent unipolar histories. Patients at the psychotic end of the continuum were more likely to be readmitted and to have very poor outcomes.

Adolescent↗

PubMed2006

Non-linear random effects model for multivariate responses with missing data.

The use of random-effects models for the analysis of longitudinal data with missing responses has been discussed by several authors. In this paper, we extend the non-linear random-effects model for a single response to the case of multiple responses, allowing for arbitrary patterns of observed and missing data. Parameters for this model are estimated via the EM algorithm and by the first-order approximation available in SAS Proc NLMIXED. The set of equations for this estimation procedure is derived and these are appropriately modified to deal with missing data. The methodology is illustrated with an example using data coming from a study involving 161 pregnant women presenting to a private obstetrics clinic in Santiago, Chile.

Algorithms↗

PubMed2006

Is self-monitoring of blood glucose appropriate for all type 2 diabetic patients? The Fremantle Diabetes Study.

OBJECTIVE: We sought to determine whether self-monitoring of blood glucose (SMBG) is associated with better glycemic control in type 2 diabetes. RESEARCH DESIGN AND METHODS: We used cross-sectional and longitudinal data from type 2 diabetic participants in the observational, community-based Fremantle Diabetes Study (FDS) who reported SMBG status at study entry (n = 1,286) and annual reviews over 5 years (n = 531). RESULTS: At study entry, 70% of patients performed SMBG, with a median of four tests per week (interquartile range two to seven). Patients with shorter diabetes duration; who were attending diabetes education, diabetes-related clinics, or medical specialists; who were taking insulin with or without oral hypoglycemic agents (OHAs); and who were self-reporting hypoglycemic events were more likely to use SMBG. Both cross-sectional and longitudinal FDS data showed that HbA(1c) (A1C) was not significantly different between SMBG users and nonusers, either overall or within diabetes treatment groups (diet, OHAs, and insulin with or without OHAs). There was also no independent cross-sectional relationship between A1C and SMBG frequency. The average annual societal cost of using SMBG (in year 2000 Australian dollars [Adollars], excluding glucometers) was 162 Australian dollars per type 2 diabetic patient or 51 million Australian dollars when projected to the Australian diagnosed type 2 diabetic population. CONCLUSIONS: Neither SMBG testing nor its frequency was associated with glycemic benefit in type 2 diabetic patients regardless of treatment. Our data did not include methods of SMBG delivery and application, factors that require further assessment in the evaluation of SMBG utility in non-insulin-treated type 2 diabetes. SMBG may be still of value in the identification and prevention of hypoglycemia and in dose adjustment in insulin-treated patients.

Aged↗

PubMed2003

The relationship between sexual assault, religiosity, and mental health among male veterans.

OBJECTIVES: We examine the association between sexual assault, religion and mental health among male veterans. METHODS: We used longitudinal data collected from 2,427 male veterans who received VA outpatient care. Sexual assault was self-reported in the questionnaire. Two dimensions of religiosity were used: organizational (frequency of religious service attendance) and subjective religiosity (the extent that religious beliefs are a source of strength or comfort). Mental health was measured by the mental component summary from the Veterans SF-36 and depression was measured by the Center for Epidemiologic Studies-Depression scale. A regression model that uses the generalized estimating equation approach for longitudinal repeated data analysis was used. RESULTS: Based on the baseline data, 96 (4%) patients reported ever experiencing sexual assault. These patients have significantly lower levels of mental health status and higher levels of depression (p < .001). The regression results show that this decrement in mental health and increment in depression associated with sexual assault are in lesser degrees for patients who attended religious service more frequently compared to those who never did (p < .05). Similarly, there is a smaller magnitude of increment in depression associated with sexual assault for those who have a higher level of subjective religiosity (p < .05). CONCLUSIONS: Although the prevalence of self reported sexual assault is low among male veterans, those who reported sexual assault experiences had lower levels of mental health status and higher levels of depression. Further, religion attenuates this association which highlights the important role religion might have in coping with this stressful life event.

Depression↗

PubMed2003

Latent transition regression for mixed outcomes.

Health status is a complex outcome, often characterized by multiple measures. When assessing changes in health status over time, multiple measures are typically collected longitudinally. Analytic challenges posed by these multivariate longitudinal data are further complicated when the outcomes are combinations of continuous, categorical, and count data. To address these challenges, we propose a fully Bayesian latent transition regression approach for jointly analyzing a mixture of longitudinal outcomes from any distribution. Health status is assumed to be a categorical latent variable, and the multiple outcomes are treated as surrogate measures of the latent health state, observed with error. Using this approach, both baseline latent health state prevalences and the probabilities of transitioning between the health states over time are modeled as functions of covariates. The observed outcomes are related to the latent health states through regression models that include subject-specific effects to account for residual correlation among repeated measures over time, and covariate effects to account for differential measurement of the latent health states. We illustrate our approach with data from a longitudinal study of back pain.

Back Pain↗

PubMed2005

Quantitative trait locus analysis of longitudinal quantitative trait data in complex pedigrees.

There is currently considerable interest in genetic analysis of quantitative traits such as blood pressure and body mass index. Despite the fact that these traits change throughout life they are commonly analyzed only at a single time point. The genetic basis of such traits can be better understood by collecting and effectively analyzing longitudinal data. Analyses of these data are complicated by the need to incorporate information from complex pedigree structures and genetic markers. We propose conducting longitudinal quantitative trait locus (QTL) analyses on such data sets by using a flexible random regression estimation technique. The relationship between genetic effects at different ages is efficiently modeled using covariance functions (CFs). Using simulated data we show that the change in genetic effects over time can be well characterized using CFs and that including parameters to model the change in effect with age can provide substantial increases in power to detect QTL compared with repeated measure or univariate techniques. The asymptotic distributions of the methods used are investigated and methods for overcoming the practical difficulties in fitting CFs are discussed. The CF-based techniques should allow efficient multivariate analyses of many data sets in human and natural population genetics.

Chromosome Mapping↗